The purpose of this Phase I feasibility study to design, construct and evaluate an ultraminiaturized sensor device capable of detect ng protein biomarkers from a few cells and, ultimately, single cells. The device, termed the nanobiosensor, consists of an array of ultraminiaturized protein captur e (antibody) domains printed on a micro fabricated silicon structure. The nanobiosensor combines concepts, methods and instrumentation from nanotechnology and cel I and molecular biology to create a pathway to single-cell proteomic analysis. The nanobiosensor will be used for monitoring both secreted and intracellular protein expression in model cell ular systems. The design of the nanobiosensor allow s the test to be brought directly to the sample origin (in this case, a cell), eliminating the difficulties associated with transporting extremely small quantities of sample extracts to a remote test site. The pr opposed research is enabled by "NanoArrayer" technology developed by the applicant institution for the construction of biochips w itch ultramicro (1-20 mm) to submicron (250 nm) spatial addresses (corresponding to 1/1000th - 1/10,000th of the surface area required for conventional microar rays tests) and requiring only extremely small sample volumes (sub-microliter to picoliter). The nanobiosensor will permit analysis of protein profiles from samples that previously could only be analyzed via PCR amplification of nucleic acids. The proposed nanobiosensor opens the door to fast and infor mative analysis of minute protein samples such as those found in forensics s ituations, neonates and tissue subpopulations (e.g., laser cell microdissected biopsy samples). This level of miniaturization translates to minimally invasive yet data-rich molecular diagnostics for early detection of cancer and other diseases with a significant reduction in patient discomfort. [unreadable] [unreadable]